modulo operator bug?

Kemal Bayram <kemal@corenetworks.co.uk>

From: Kemal Bayram <kemal@corenetworks.co.uk>
To: pgsql-bugs@postgresql.org
Date: 2001-03-13T22:29:10Z
Lists: pgsql-bugs
from psql:

kemal=# select 0.99 % 0.50;
 ?column? 
----------
     0.04
(1 row)

Am I missing something fundemental here or is this indeed a bug?